Project Summary/Abstract Adults with intellectual and developmental disabilities (IDD) represent an underserved segment of the US population with a high prevalence of obesity, obesity related chronic disease, and limited options for weight management. We have demonstrated clinically meaningful weight loss of 6.4% and 7.0% in 2 trials in adults with IDD using an enhanced Stop Light Diet (eSLD) in combination with monthly at-home face-to-face (FTF) behavioral sessions (adult/caregiver), and a recommendation for increased physical activity (PA). The eSLD recommended daily consumption of 2 ~ 200 kcal portion-controlled entres, 2 ~100 kcal shakes, 5 servings of fruits/vegetables, and ad-libitum non-caloric beverages and additionally low energy foods selected using the SLD system: green (low energy), yellow (moderate energy), and red (high energy). Although this intervention produced significant weight loss, the time and cost associated with FTF delivery (travel + sessions) limits the potential for scaling and implementation, and suggests the need for the evaluation of less costly and burdensome strategies for intervention delivery. Therefore, we propose a 24 mo. randomized trial to compare 2 weight management interventions (6 mos. weight loss, 12 mos. maintenance, 6 mos. no-contact follow-up) delivered to adults with IDD in their home, either remotely (RD) using video conferencing (Zoom software) on a tablet computer (iPad mini), or during FTF visits. Both intervention arms will include individual monthly at-home behavioral sessions (participant & caregiver), an eSLD, and increased PA. The RD arm will include group PA (2 session/wk.) delivered using video conferencing and will use commercially available web-based applications for self-monitoring/participant feedback for diet (Lose it!), PA (Fitbit activity tracker), and weight (Wi-Fi scales). The FTF arm will be identical to the intervention shown to be effective in our previous trial (DK83539) and will include self-directed PA, self-monitoring of diet and PA using paper and pencil self-reports, and weight assessed during monthly home visits. The primary aim will determine whether RD is non-inferior to FTF for weight loss (0-6 mos.). Non-inferiority will be declared if mean weight loss for RD is no worse than FTF, within statistical variability, by a margin of -3 kg. Secondarily we will compare the RD and FTF groups on mean weight loss, the proportion of participants who achieve clinically meaningful weight loss, and changes in quality of across 24 months. We will also conduct cost, cost-effectiveness and contingent valuation analyses to compare the RD and FTF groups. We will also explore the influence of behavioral session attendance, compliance to recommendations for diet (energy intake, number of entres/shakes, servings of fruits/vegetables, PA (min of moderate-vigorous PA), self-monitoring of diet and PA, sex, age, IDD diagnosis, caregiver self-efficacy/turnover, and obesogenic medications on weight loss across 18 months.